Sexuality - how many variations are there?

Everyone is familar with the main four sectors:

• Gay
• Lesbian
• Bisexual 
• Heterosexual

However there are other sexual orientations such as pansexual - this means that they are attracted to people regardless of their gender. Those of you who follow Skins many of you will be familiar with the term as Frankie is pansexual.  Pansexuals appear to be the most accommodating as they see the individual rather than imposing sexual classifications, the best definition I have come across is on Yahoo answers; to read it for yourself feel free to follow this link: http://uk.answers.yahoo.com/question/index?qid=20100224141538AAVV8mi